This invention relates to sprinkler systems and, more particularly, to a fire extinguishant sprinkler system designed to operate in freezers and other cold environments.
Sprinkler systems for extinguishing fires in large storage freezers and in other cold environments at freezing temperatures wherein the piping leading to the sprinkler heads extend through the freezing environment have to be designed in a way to prevent extinguishant in the piping from freezing. One way to accomplish this objective is to use a dry pipe system wherein the piping in the freezing environment leading from a water supply under pressure is maintained dry and filled with air or other gas. When a sprinkler head is activated in response to a fire beneath the sprinkler head, water must travel from the source of supply through the piping to sprinkler head before the water is sprayed onto the fire. As a result, an unacceptably long delay between the time the sprinkler head is activated and the time that the sprinkler head begins to discharge water occurs and the desired early suppression fast response for large storage systems is not achieved. In some wet pipe systems for freezing environments, propylene glycol is used to fill the piping leading to the sprinkler heads, but when propylene glycol is used in concentrations sufficient to prevent freezing, the solution is flammable and, therefore, its effectiveness in a sprinkler system is substantially compromised. A calcium chloride solution would prevent freezing, but it is corrosive and thus would increase the property damage when the sprinkler system is activated. Other solutions that might be used in a wet pipe sprinkler system are glycerine, methanol, potassium acetate and urea. However, each of these solutions raise concern from a combustibility, corrosivity and/or environmental safety standpoint. Accordingly, there is a need for an effective early suppression, quick response, sprinkler system for freezers and other cold environments in which the piping leading the sprinkler heads passes through low temperature environments substantially below the freezing point of water.
In accordance with the present invention, a sprinkler system for use in freezers and other cold environments is provided wherein the piping passing through the low temperature environment is filled with a selected solution of potassium lactate. The piping is connected to a conventional water supply under pressure through a check valve. The pressure of the potassium lactate solution in the piping is maintained above the water pressure in the source of water supply so the check valve remains closed when no sprinklers have been activated. The concentration of the potassium lactate in the aqueous solution is selected to be high enough to prevent the solution from freezing in the sprinkler system piping and yet low enough to prevent the viscosity of the solution from interfering with the flow rate in standard sprinkler system piping. For any practical application, the concentration of potassium lactate should be between 30% and 60% by weight. For freezer and cold environments at 10xc2x0 F., a potassium lactate concentration of 30% by weight can be used. For most applications, the concentration of the potassium lactate should be between 40 and 50 percent by weight. For freezers and cold environments at temperatures between 16xc2x0 F and 0xc2x0 F., a 40% solution by weight of potassium lactate is used. For sharp freezers wherein the temperature is maintained between 0xc2x0 and xe2x88x9220xc2x0 F., a 47% solution by weight of potassium lactate is preferably used. In the system, a tank containing the potassium lactate solution is connected to the piping and a jockey pump is provided to pump an additional volume of potassium lactate into the piping to provide a make up for potassium lactate lost from the piping due to leakage and to maintain the pressure in the piping above that of the source of water supply.
When the sprinkler head is actuated, the potassium lactate in the piping leading to the sprinkler head will be sprayed from the sprinkler head reducing the pressure in the piping below the pressure in the water supply and the check valve between the water supply and the sprinkler system piping will open. Water will then flow from the water supply through the piping to the actuated sprinkler head.
Potassium lactate in the right concentration is highly suitable to be used in the sprinkler system piping because it is not flammable, is not corrosive, is nontoxic and is environmentally safe. In fact, potassium lactate is edible and is frequently used as a food additive. It is also effective as a fire extinguishant.